Using pre-bent chain links which are still open at one point, which are welded by electrical resistance and flash butt welding to form closed chain links and to form a chain, for producing welded round and profile steel chains is known.
These chain links are typically produced from wire rolls (coils) or from bars (in the case of diameters from approximately 22 mm), the latter being cut on bending machines into individual stubs (pins), these being bent into open chain links, and the latter being connected to form a (not yet welded) chain. These pre-bent chain links are finally welded to form peripherally closed links and thus to form the finished chain in resistance butt welding or flash butt welding machines.
As a result of the bending procedure required in this case, only round wires and profile wires having simple cross-sections may be processed into a chain, in contrast, chain links having complicated cross-sections and having varying cross-sections are not producible using the known bending.
The specified welding methods also significantly restrict the scope of the materials and alloys usable for the chain production, so that, for example, steels having carbon contents of greater than 0.25% are no longer weldable using the listed fusion welding methods because of the danger of cracking occurring upon bending. The known friction welding methods, using which steels having higher carbon contents and many other iron and nickel alloys may also be welded, is precluded for the welding of such pre-bent chain links, however, because the butt surfaces to be welded must be moved oscillating relative to one another and in parallel in an axially-deviating manner during the friction welding, which is not feasible in the case of pre-bent chain links because of the danger of a fatigue fracture.